Power brakes, power press brakes, press brakes, presses, punches, and shears usually perform an operation on a part such as an article being manufactured. One type of operation involves the bending of a flat sheet of metal to form a lip, flange and other shapes. This is usually accomplished by setting the metal sheet on a die having the desired shape then causing a ram having a pointed edge along its length to impact the metal sheet and push the metal sheet into the die thereby bending the metal sheet into the form of the die. A common case involves a V-shaped die and a ram having an edge with a long length that is centered above the middle of the V.
It is normally desired to place the bend in the part at a specified distance from the edge of the part. This may be done by measuring the distance from the edge of the part to the center of the die. In the past this measurement has been done by trial and error whereby the distance is visually estimated then the bend is placed in the part and then the location of the bend is measured after the bend has been made. If the bend is not in the right place, then the position of the part on the die is visually adjusted and the process is repeated until the bend is placed in the right spot. This procedure has the disadvantages of being inaccurate, unduly time consuming, waseful of parts, requires subjective estimations of distances, unsuitable for placing bend in correct spot on first attempt, and nonrepeatability, among others.
Another procedure involves measuring the distance from the center of the die to the edge of the part with a ruler or a measuring device of the desired length. This procedure has the disadvantage of being inaccurate and not being precisely repeatable, among others. Other procedures use reference bars which have the disadvantages of having to have to be removed prior to the operation on the part and inability to make multiple measurements at one time and require several experimental operations in order to produce the bend in the right place on the part.